The present invention relates to devices used to maintain and monitor the integrity of sealed containers and devices. More specifically, the invention relates to electronic tamper detection devices.
In commerce, there are a myriad of situations requiting the integrity of a sealed container to be maintained and monitored. For example, utilities equipment located in publicly accessible areas (e.g. electric power meters and cable TV hookups) is typically sealed in containers with a clasp having a crimped lead seal. Any tampering with the equipment can be detected by a break or removal of the original seal. Another example is provided by electronics equipment that may use a paper seal across screws or other components of the exterior case to prevent undetected entry and possible modification of the circuitry. As yet another example, pallets of individual items may be wrapped in plastic sheeting and secured with a specially marked or formulated adhesive strip which prevents disassembly of the pallet without visible damage to the sealing strip.
In an effort to improve upon the simple lead crimp-type seal mentioned above, numerous other shackle-type sealing devices have been developed for sealing and allowing detection of tampering with containers. See, e.g., U.S. Pat. Nos. 5,127,687 (Guiler); 5,056,837 (Fuehrer); 5,005;883 (Guiler); 4,946,210 (Fuehrer) 4,883,295 (Kesselman); 4,811,977 (Swift et al.). In addition to utilities equipment box applications, such devices are described as suitable for use, alone or in conjunction with separate heavy-duty locking means (e.g., a padlock), to secure cargo containers (e.g., semi-tractor trailers, railway cars and the like), and to prevent and detect tampering with mechanical/electrical devices such as railway and high-voltage switches.
The practice of sealing goods and equipment used in commerce, to ensure that they have not been opened, altered, removed or otherwise tampered with, will be referred to as "bonding." All of the aforementioned bonding arrangements require a visual inspection of a device to determine whether a seal violation has occurred. Such arrangements are less than ideal for certain applications in that they do not allow for such detection from a distance (i.e., remote detection). Instead of relying solely on a visual inspection, U.S. Pat. No. 5,120,097 (Fattori et at.) discloses a shackle-type seal incorporating a conductive strip and contact points that allow a manual check of electrical continuity as evidence of tampering. This sealing arrangement likewise requires an individual up-close check to see whether the seal has remained intact.
The ability to remotely electronically monitor the status of a plurality of seals would significantly reduce the time and effort required to perform individual checks. For example, within a warehouse there may be a great many items which have been sealed, and it may be necessary or deskable to periodically verify that the seals within the warehouse are all intact. To do so would conventionally require one or more persons to travel throughout the warehouse to individually inspect and record the status of each seal. Such manual checking is not only time and labor intensive, but is also prone to human error. On the other hand, remote electronic monitoring of seals would allow complete automation of the task by computer, thereby substantially reducing human labor and error.
Another situation wherein remote sensing would be highly useful arises in connection with trucks used to convey one or more bonded items, e.g., containers, or wrapped (bonded) pallets of individual items. At various times during transit it may be necessary or desirable to verify the seal(s), such as when the track leaves the point of origin, or when it passes through an international border. In such cases, it would be advantageous to have a means for verifying the seal(s) which does not require that the truck stop for inspection.
The need for alternative methods of bonding is becoming more acute as electronic transactions become more and more prevalent. For example, many governments are examining methods of arranging for goods to cross their borders whereby all customs and other information is passed electronically.
U.S. Pat. No. 4,750,197 (Dennekamp et al.) discloses a system for remotely monitoring cargo trip data. The system includes door mounted magnetic sensors for sensing the opening of a large freight container, e.g., a semi-truck trailer, and a cellular telephone for transmitting trip information, including signals from the door sensors, to a central processing facility.
U.S. Pat. No. 5,025,253 (DiLullo et al.) discloses a system for remotely checking the connect/disconnect status of a semi-tractor trailer. A cab mounted interface unit (IFU) is connected with an electronic tag (identifier) located on the trailer, through the truck's 12 volt power bus. When the trailer is disconnected, the IFU senses the absence of the electronic tag, and this result is transmitted to a central station via an on-board satellite transmitter.
The above two systems may be useful for monitoring whether a truck trailer or the like has been disconnected or opened, but both form an integral part of the vehicle. Thus, neither is suitable for direct application to an outside of multiple individual items, e.g., the cargo within a trailer, to thereby individually bond the items.